Device in a cutter, particularly in a paper bag tube machine



Dec. 20, 1966 u. MANTOVAARA DEVICE IN A CUTTER, PARTICULARLY IN A PAPER BAG TUBE MACHINE Filed Nov. 24, 1964 United States Patent 3,292,474 DEVICE IN A CUTTER, PARTICULARLY IN A PAPER BAG TUBE MACHINE Urpo Mantovaara, Pori, Finland, assignor to W. R osenlew & C0., 0y, Pori, Finland, a corporation of Finland Filed Nov. 24 1964, Ser. No. 413,4 0 Claims priority, application Finland, Nov. 29, 1963, 2,361/ 63 4 Claims. (Cl. 83-327) This invention relates to a cutter intended principally for cutting paper bag tubes. It includes a beam that holds cutting and/or perforating blades. This beam is carried eccentrically in bearings in an end disk attached to a rotating central shaft and receives its rotation via a planet gear set. Thus the blade and counterpiece, which are arranged in a suitable manner, remain parallel to each other and to the paper-strip being cut during the whole cutting operation. In this way, stepped shapes, and others involving cutting in a longitudinal direction, can be cut in a single phase, whereas otherwise two consecutive cutters of a simpler design would be required.

Another notable advantage of this type of cutter is that by modifying the gear transmission to the beam, the latter can be caused to make a turn after each cutting operation. This enables the blades to by-pass every other cutting operation, or two blades to out different shapes in turn, for instance in an saving cut for valve tubes intended to be sewn.

Two devices designed for this purpose are prior known.

In both, the central wheel of the planet gear transmis- A device in which the planet wheel set consists of an elliptical eccentric pair of wheels, the central cogwheel of which is stationary, has also been proposed. In this device the rotation of the beam is in fact a smooth one; the motion required is provided by the elliptical gears, but there are no jerky movements. The defect of this device is that its function cannot be changed, so that two blades are needed even when only a single shape is being cut, which is very often the case in practice. This arrangement is cumbersome when small tube series are being run, necessitating frequent changes of blades.

The object of our invention is a device in which the defects described above are eliminated so that the beam rotates without jerky movements and the device can be adjusted by simple means to cut different shapes.

In our invention this is achieved by making the planet gear set a pair of cylindrical cogwheels, the central one of which rotates constantly and is linked to the central shaft via two pairs of cogwheels and an intermediate shaft carried in hearings in the casing of the machine.

In one advantageous embodiment of the invention, one of the pairs of cogwheels that link the planet gear set to the central shaft is carried in bearings outside the casing of the machine so as to facilitate its exchange.

For cutting certain shapes, the exchangeable pair of cogwheels can be elliptical and eccentric or cylindrical in shape, or else the smaller wheel can be elliptical and the bigger wheel oval, almost elliptical, in shape.

The invention is described below in greater detail, with reference to the embodiment shown in the accompanying drawings. FIG. 1 is a cross-sectional view of the cutter according to the invention seen through one end. For

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simplicitys sake, the sectional cuts have been made on different radial planes. FIG. 2 shows gear wheel pairs in the device. FIG. 3 shows the circular movement of the beam diagrammatically.

D in FIG. 1 is the end disk attached to the revolving central shaft So. The beam B rotates eccentrically in hearings in the disk D. To the beam B is attached fast a cylindrical gear wheel 1, with which is meshed a planet wheel 3 carried in bearings in the end disk. The central wheel 2 of the planet gear set is carried in bearings on the central shaft and rotates idly on it. The central wheel 2 is linked to the central shaft Sc by two pairs of gear wheels 4, 5 and 6, 7. Wheel 4 is made integral with the central wheel 2, wheels 5 and 6 are attached fast to an intermediate shaft Si, which is carried in hearings in the casing C of the machine, and wheel 7 is attached fast to the central shaft Sc. Thus the central wheel 2 rotates continuously with respect to the casing C of the device.

In this embodiment the gear wheel pair 6, 7 is located in its own housing H outside the main casing C, so that it can easily be exchanged to enable different shapes to be cut out of the tube. In the embodiment shown in FIG. 1 (and solid lines in FIG. 2) the wheel pair 6, 7 is a pair of elliptic eccentric cogwheels, the biggest and smallest turning radii of the wheels being a and b, respectively. The speeds of rotation of gears 6 and 7 thus vary cyclically with respect to each other. The device presented functions correctly when the gear ratio and radii of the elliptical wheels conform to the following equations:

and

vice by exchanging only the pair of cogwheels situated outside the casing of the machine. By selecting a:b=2:3, r :r =1:2 and r :r =4:3, a co-gwheel set with the rotation curves shown in FIG. 2 is obtained.

The first alte-mative n is obtained by means of a pair of elliptical cogwheels 6, 7, which are shown in solid lines and have a gear ratio of r :r =l:1.

The second alternative n =0 is obtained by means of a pair of cylindrical wheels 6, 7, shown in dash-and-dot lines, the gear ratio of which r :rb:a=3:2.

The third alternative which is seldom required in practice, is obtained by means of a cogwheel pair 6", 7", shown by broken lines, in which the smaller wheel is elliptical and the bigger wheel in a shape of an over resembling an ellipse. Here the gear ratio r :r =2: 1.

In the first alternative, therefore, the beam rotates or is indexed through in the same direction as the central shaft for each revolution of the cutter. The positional error of the beam due to the play in the parts of the device (angle '7 in FIG. 3) is insignificant in the cutting area. In a cutter in which the turning radius groove in the counterpiece to a depth of 5 mm., for instance, a cutting area within an angle range of g=i9 on both sides of the lowest position of the blade is obtained. The maximum positional error of the beam in this case is 'y=i( .01. The corresponding shift of the blade edge in the groove of the counterpiece is 0.01 mm. when the height of the blade edge from the beam shaft is 65 mm.

The above theoretical positional error can be reduced even further by making the eccentricity of the elliptical wheels slightly greater than that indicated in equation I. In this case, the position of the beam will be exactly right at three points and the maximum error will lie between these positions. In practice, the most important factor is the angle of error caused by the play in the moving parts, but this is easy to control in the invention, since the play between the gear teeth can be regulated in a prior-known manner, for instance by splitting the circumference of one wheel of each pair of wheels into halves adjustable in relation to each other, as shown in the gear wheels and 6 in FIG. 1. In the case of the elliptical wheels, of course, the wheel to be split is the one that has the biggest radius during the cutting operation.

In the second alternative presented above, the beam remains parallel at all positions, and thus the only angles of error are those caused by the play in the moving parts.

In the third alternative, cutting can be performed with four different blades, and the positional error of the beam due to the play in the parts of the device is of the same small magnitude as that described above in the case of the first alternative.

The invention is not limited to the embodiment described above and shown in the drawings, but can be varied in different ways within the scope of the invention. For example, different sorts of cogwheel sets can be used in special cases.

What I claim is:

1. A device adapted for cutting paper, said device comprising a rotatable main shaft, frame means journallin-g the main shaft, a disc secured to the main shaft for rotation therewith, a rotatable beam parallel to the main shaft and journalled in the disc eccentrically of the main shaft, at least two cutting means on said beam, said two cutting means lying generally radially of the beam and at an angle with respect to each other for successive presentation to a cutting station as the main shaft rotates, and positively connected gear means connecting the central shaft and said beam to each other so that the beam turns smoothly about its axis between cutting operations but remains parallel with itself during each passagethrough the cutting station, said gear means comprising a first gear secured to the beam for rotation therewith, a second gear journalled coaxially of the main shaft for rotation with respect thereto, a third, planet gear journalled eccentrically of the main shaft for rotation as a, whole thereabout, said third gear being in positive mesh with both the first and the second gears so as to keep such configuration that their speeds of rotation relative to each other vary cyclically.

2. A device as claimed in claim 1, wherein the pair of meshing gears the speeds of rotation of which relative to each other vary cyclically are elliptical eccentric gear wheels having fixed axes of rotation.

3. A device as claimed in claim 1, wherein said frame means is in the form of a casing, and wherein said train of positively meshing gears include an exchangeable pair of meshing gears disposed outwardly of said casing.

4. A device as claimed in claim 1, wherein said positive driving means comprises a fourth gear aflixed to and rotatable with the main shaft, an intermediate shaft journalled in said frame means, a fifth gear afiixed to the intermediate shaft and meshing with the fourth gear, a sixth gear afiixed to the intermediate shaft for rotation therewith, and a seventh gear integrally connected to the second gear and rotatable about the axis of the main shaft and with respect to said main shaft.

References Cited by the Examiner FOREIGN PATENTS 1,060,235 6/1959 Germany.

WILLIAM S. LAWSON, Primary Examiner. 

1. A DEVICE ADAPTED FOR CUTTING PAPER, SAID DEVICE COMPRISING A ROTATABLE MAIN SHAFT, FRAME MEANS JORNALLING THE MAIN SHAFT, A DISC SECURED TO THE MAIN SHAFT FOR ROTATION THEREWITH, A ROTATABLE BEAM PARALLEL TO THE MAIN SHAFT AND JOURNALLED IN THE DISC ECCENTRICALLY OF THE MAIN SHAFT, AT LEAST TWO CUTTING MEANS ON SAID BEAM, SAID TWO CUTTING MEANS LYING GENERALLY RADIALLY OF THE BEAM AND AT AN ANGLE WITH RESPECT TO EACH OTHER FOR SUCCESSIVE PRESENTATION TO A CUTTING STATION AS THE MAIN SHAFT ROTATES, AND POSITIVELY CONNECTED GEAR MEANS CONNECTING THE CENTRAL SHAFT AND SAID BEAM TO EACH OTHER SO THAT THE BEAM TURNS SMOOTHLY ABOUT ITS AXIS BETWEEN CUTTING OPERATIONS BUT REMAINS PARALLEL WITH ITSELF DURING EACH PASSAGE THROUGH THE CUTTING STATION, SAID GEAR MEANS COMPRISING A FIRST GEAR SECURED TO THE BEAM FOR ROTATION THEREWITH, A SECOND GEAR JOURNALLED COAXIALLY OF THE MAIN SHAFT FOR ROTATION WITH RESPECT THERETO, A THIRD, PLANET GEAR JOURNALLED ECCENTRICALLY OF THE MAIN SHAFT FOR ROTATION AS A WHOLE THEREABOUT, SAID THIRD GEAR BEING IN POSITIVE MESH WITH BOTH THE FIRST AND THE SECOND GEARS SO AS TO KEEP THE BEAM PARALLEL TO ITSELF DURING EACH OF ITS PASSAGES THROUGH THE CUTTING STATION, AND POSITIVE DRIVING MEANS INCLUDING A TRAIN OF POSITIVELY MESHING GEARS CONNECTED BETWEEN THE MAIN SHAFT AND THE SECOND GEAR FOR INDEXING THE BEAM ABOUT ITS AXIS IN THE INTERVALS BETWEEN THE PRESENTATION OF THE BEAM TO THE CUTTING STATION, SAID TRAIN OF POSITIVELY MESHING GEARS INCLUDING A PAIR OF MESHING GEARS OF SUCH CONFIGURATION THAT THEIR SPEEDS OF ROTATION RELATIVE TO EACH OTHER VARY CYCLICALLY. 